1. Field of the Invention
The present invention relates to integrated circuits and more particularly generating a reference signal in integrated circuits.
2. Description of the Related Art
In general, a bandgap reference circuit provides a voltage reference with improved temperature stability and is less dependent on power supply voltage than other known voltage reference circuits. Bandgap reference circuits typically generate a reference voltage approximately equal to the bandgap voltage of silicon extrapolated to zero degrees Kelvin, i.e., VG0=1.205V. Typical voltage reference circuits include a current minor coupled to the power supply and the voltage reference node to provide a current proportional to absolute temperature (i.e., PTAT) to the voltage reference node. These circuits can be made with relatively low cost, but have the disadvantages of being sensitive to mechanical strain and/or aging, which reduces the accuracy of the voltage reference. In addition, typical voltage reference circuits generate PTAT (or equivalent) output currents that vary across temperature, which make those voltage references less useful as standalone current generators. An additional voltage-to-current generator is typically used to stabilize the output current.
Accordingly, improved techniques for generating reference voltages are desired.